This project focuses on leiomyomata (fibroids) and examines factors related to their pathogenesis, diagnosis and/or potential treatment. Ongoing work seeks to evaluate the utility of the progesterone response modulator CDB2914 as a treatment of fibroids. We previously investigated the effect of single doses of the agent on the menstrual cycle in women, and showed that doses of 100 or 200 mg retard folliculogenesis and precipitate menses, in the follicular and luteal phase respectively. A recently completed study showed reduction in fibroid size in women receiving CDB 2914 at a daily dose of 10 or 20 mg for three months, as compared to women receiving placebo. An ongoing randomized double-blind clinical trial evaluates whether CDB 2914 has additional inhibitory effect during a six month treatment, and also evaluates the duration of the inhibition of growth after treatment is discontinued. We also are using gene arrays to evaluate the pathophysiology of leiomyomata.